title: Blockade of Adrenal Medulla-Derived Epinephrine Potentiates Bee Venom-Induced Antinociception in the Mouse Formalin Test: Involvement of Peripheral β -Adrenoceptors.
abstract: The injection of diluted bee venom (DBV) into an acupoint has been used traditionally in eastern medicine to treat a variety of inflammatory chronic pain conditions. We have previously shown that DBV had a potent antinociceptive efficacy in several rodent pain models. However, the peripheral mechanisms underlying DBV-induced antinociception remain unclear. The present study was designed to investigate the role of peripheral epinephrine on the DBV-induced antinociceptive effect in the mouse formalin assay. Adrenalectomy significantly enhanced the antinociceptive effect of DBV during the late phase of the formalin test, while chemical sympathectomy had no effect. Intraperitoneal injection of epinephrine blocked this adrenalectomy-induced enhancement of the DBV-induced antinociceptive effect. Moreover, injection of a phenylethanolamine N-methyltransferase (PNMT) inhibitor enhanced the DBV-induced antinociceptive effect. Administration of nonselective β -adrenergic antagonists also significantly potentiated this DBV-induced antinociception, in a manner similar to adrenalectomy. These results demonstrate that the antinociceptive effect of DBV treatment can be significantly enhanced by modulation of adrenal medulla-derived epinephrine and this effect is mediated by peripheral β -adrenoceptors. Thus, DBV acupoint stimulation in combination with inhibition of peripheral β -adrenoceptors could be a potentially novel strategy for the management of inflammatory pain.
authors.affiliation: Department of Veterinary Physiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Suk-Yun
authors.initials: SY
authors.lastname: Kang
authors.forename: Dae-Hyun
authors.initials: DH
authors.lastname: Roh
authors.forename: Hyun-Woo
authors.initials: HW
authors.lastname: Kim
authors.forename: Ho-Jae
authors.initials: HJ
authors.lastname: Han
authors.forename: Alvin J
authors.initials: AJ
authors.lastname: Beitz
authors.forename: Jang-Hern
authors.initials: JH
authors.lastname: Lee